[KLUG Members] Iptables

[Bruce Smith]

> > >I've never tried blocking the instant messenger services.
> > >Why don't you just try it and see if it works?
> > Trying to block some of these can get tricky, since they can
> > be configured to use http and https for their operation. I'm
> > sure some network administrators can get away with blocking
> > these, but I haven't met one recently.
> 
> Yep, they are basically unstoppable without breaking basic
> functionality.  I've yet to see a reliable way of smacking these
> parasitic services.

I block the default operation of IM services (not sure about http
configured IM's) by only allowing access to the internet through my
authenticated squid server.

Unless a client supports an authenticated proxy, and my squid config
allows the required ports, my users don't go there.

 - BS